The linkage between the East Antarctic Ice Sheet fluctuations and global climate changes during the Plio-Pleistocene

第3回極域科学シンポジウム　横断セッション「海・陸・氷床から探る後期新生代の南極寒冷圏環境変動」11月27日（火） 国立国語研究所 ２階講

A Reconstruction of Subtropical Western North Pacific SST Variability Back to 1578, Based on a Porites Coral Sr/Ca Record from the Northern Ryukyus, Japan

We present a seasonal reconstruction of sea surface temperature (SST) from 1578 to 2008, based on a Porites coral Sr/Ca record from the northern Ryukyus, within the Kuroshio southern recirculation gyre. Interannual SST anomalies are generally similar to 0.5 degrees C, making Sr/Ca-derived SST reconstructions a challenging task. Replicate measurements along adjacent coral growth axes, enabled by the laser ablation inductively coupled plasma mass spectrometry technique used here, give evidence of rather large uncertainties. Nonetheless, derived winter SST anomalies are significantly correlated with the Western Pacific atmospheric pattern which has a dominant influence on winter temperature in East Asia. Annual mean SSTs show interdecadal variations, notably cold intervals between 1670 and 1700 during the Maunder Minimum (MM) and between 1766 and 1788 characterized by a negative phase of the North Atlantic Oscillation. Cold summers in 1783 and 1784 coincide with the long-lasting Laki eruption that had a profound impact on the Northern Hemisphere climate, including the severe Tenmei famine in Japan. The decades between 1855 and 1900 are significantly cooler than the first half of the twentieth century, while those between 1700 and 1765, following the MM, are warmer than average. SST variability in the Ryukyus is only marginally influenced by the Pacific Decadal Oscillation, so that external forcing remains the main driver of low-frequency temperature changes. However, the close connection between the Kuroshio extension (KE) and its recirculation gyre suggests that decadal SST anomalies associated with the KE front also impact the Ryukyus, and there is a possible additional role for feedback of the Kuroshio-Oyashio variability to the large-scale atmosphere at decadal timescale.Part of this research was supported from a grant by JSPS KAKENHI (JP15KK0151 and JP17H01168) to Y. Y. Data used in this paper are provided as supporting information (Table S2)

Gauging Quaternary Sea revel Changes Through Scientific Ocean Drilling

Indicators of past sea level play a key role in tracking the history of global climate. Variations in global sea level are controlled mainly by growth and decay of continental glaciers and temperatures that are closely correlated with the mean global climate state (glacial and interglacial cycles). Our understanding of global climate and sea level has benefited significantly from improvements in ocean floor sampling achieved by the Ocean Drilling Program (ODP) and the Integrated Ocean Drilling and International Ocean Discovery Programs (IODP), as well as from the application of new analytical techniques and isotope mass spectrometry. This paper presents an overview of recent advances in paleo-sea level studies based on analysis of samples and data from deep-sea sediment cores and drowned coral reefs obtained through ODP and IODP. Future scientific ocean drilling will contribute further to studies of ice sheet dynamics under different climatic boundary conditions.Financial support of this research was provided by the JSPS KAKENHI (grant numbers JP15KK0151, and JP17H01168)

Ocean front migration over the Conrad Rise in the Indian Sector of the Southern ocean since the last glacial maximum

第3回極域科学シンポジウム　横断セッション「海・陸・氷床から探る後期新生代の南極寒冷圏環境変動」11月26日（月） 国立国語研究所 ２階講